Composite alloy



1953 T. E. LEONTIS ET AL 2,659,134

COMPOSITE ALLOY Filed Aug. 16, 1950 INVENTORSQ Thomas E. Leon/11S i yRober/ S. Busk A TTORNE Y6 m v A W M Patented Nov. 17, 1953 UNITED STATSQFFICE COMPOSITE ALLOY ware Application August 16, 1950, Serial No.179,777

2 Claims.

The invention relates to a magnesium-base alloy article. It moreparticularly concerns a zinc-containing magnesium-base composite alloyhaving a high tensile strength and the lightness characteristic ofmagnesium.

The term magnesium-base alloy used herein means a magnesium alloycontaining at least 80 per cent of magnesium by weight.

The invention is predicated upon the discovery that by die-expressing atelevated temperature a zinc-containing magnesium-base alloy inparticulated form in admixture with particulated aluminum a highstrength composite alloy extrusion is obtained. The composite alloyextrusion of the invention has the same compactness and. integrity asthe usual magnesium-base alloy extrusions made by extruding a solidmass, such as an ingot of a magnesium-base alloy, but the metallographicstructure of the composite product is uniquely different. Metallographicexamination reveals a new type of structure in a magnesium-base alloyarticle. The structure is essentially multimetallic. Each of theparticulated metals of the mixture which is extruded is changed to theform of elongated particles with the long axis parallel to that of theextrusion. The elongated particles are all welded one to the other intoa solid mass without voids forming a product which may be subjected toall the metal working operations in use with conventional magnesium-basealloys, such as rolling, forging, drawing, welding, electroplating, heattreating, etc. The invention then consists of the compositemagnesium-base alloy product and method of making the same herein fullydescribed and 3 particularly pointed out in the claims, the followingdescription setting forth several modes of practicing the invention.

In carrying out the invention, various aluminum-and zirconium-freemagnesium-base alloys containing zinc may be used, such as thosecontaining from about 0.5 to 8 per cent of zinc. It is advantageous toinclude in the zinc-containing magnesium-base alloy a conventionalamount of manganese, e. g. from about 0.1 to 2.5 per cent, a generallydesirable amount being about 1 per cent. If desired, the alloy also maycontain calcium in amount up to 1.0 per cent, or copper in amount up to0.5 per cent. The zinc-containing magnesium-base alloy, used as one ofthe in gredients of the composite alloy of the invention, is reduced toparticulate form in any suitable way, such as by grinding or atomizing.The atomized form yields superior results and may be produced by forminga melt of the alloy and atomizing it by impinging a jet of a cool gas,e. g. natural gas, against a thin falling stream of the molten alloy.The atomized alloy consists of a mixture of various sized fine sphericalrapidly solidified particles, the particles having a very fine grainstructure. It is desirable to screen out particles coarser than thosepassing about a 10 to 20 mesh standard sieve.

The aluminum ingredient of the mixture of particulate metals to beextruded according to the invention, is elementary aluminum which hasbeen finely divided in any convenient manner. Its particle size ispreferably made finer than that of the zinc-containing aluminumandzirconium-free magnesium-base alloy with which it is to be mixed.

Before extrusion, the particulated metals are mixed together in anyconvenient manner to form a uniform mixture of the metal particlescomprising the extrusion charge. The relative amounts of theparticulated zinc-containing magnesium-base alloy and particulatedaluminum are adjusted so that there is at least 0.1 part by weight ofthe particulated aluminum per 100 parts of the mixture. Beneficialresults are had with up to as much as about 6 parts of particulatedaluminum per 100 parts of the mixture. A preferred proportion is about 3parts of the particulated aluminum per 100 parts of the mixture.

The mixture of particulated metals is charged into the heated containerof a ram extruder, having a suitable size container and die opening andsubjected to extrusion pressure to cause the mixture of particulatedmetals to be heated and extruded through the die opening.

As to the extrusion conditions, the temperature of the particulatedmetal mixture in the con tainer may be about the same as thatconventionally employed for extruding solid ingots of the knownzinc-containing aluminum-freemagnesium-base alloys, e. g. 600 to 800 F.The ratio of the cross-sectional area of the extrusion container to thatof the die opening has a material efiect on the mechanical properties ofhe composite extrusion product obtained. A desirable ratio is at leastabout 30 to 1, although ratios as high as 150 to 1 or more may be used.The speed of extrusion may be varied over a wide range and depends tosome extent upon the size and shape of the die opening. In any case, theextrusion speed is to be held down to that at which the extrusionproduced is free from hot shortness. A safe extrusion speed may beascertained by visual examination of the product as it extrudes, the hotshortness being evident as 3 cracks in the extruded product and sharplyreduced strength. The composite extrusion prod uct may be subjected toany of the fabrication operations conventionally in use with the con- Byputting a charge of the mixture of the metals involved under pressurewhile at heat, as with the apparatus shown, the mixture of metalparticles is compacted but not subjected to furventional ornon-composite magnesium-base al- 5 ther mixing before extrusion. Themetals origiloys, such as rolling, forging, drawing and weldnally in thecharge as individual metal particles ing, and its tensile properties maybe enhanced do not lose their original distinctive composition by heattreatment. except at the surfaces of the union of the differ- Theinvention may be further illustrated and out metal particles whichbecome extended and explained in connection with the accompanying llengthened during extrusion. At these surfaces, drawing in which: duringextrusion or heat treatment, some diffu- Fig. 1 shows a schematicsectional elevation sion of metal takes place between the zinc-conof anextrusion apparatus suitable for use in taining particles and thealuminum particles, practicing the invention; forming composite alloy.

Fig. 2 is a similar view to Fig. 1 showing a 15 The following examples,set forth in the table modification of the apparatus; and below, areillustrative of the invention:

Table Com osition of extrusion charge of particulated Mg Mechanicalpropertiesin 1,000 5.1.

alloy mixed with particulated aluminumv Exmislon 9mm of extrusions 1Example O. Blank Weight Weight Redw Extrusion ASK Aged 11.1. H.T.A.

Analysis of Mg alloy 5:5, T???" tion in diameter,

alloy Al area TYS TS TYs TS TYS 'IS 'lYS is 99.9 1.13% Z11, balance Mg0.1 34:1 44 30 43 24 3 26 37 99. .do 05 34:1 41 34 42 37 20 33 3 94.0 do0.0 34:1 40 30 40 32 41 42 Blank 1...- 100 .do None 34:1 33 39 24 30 2241 4 99.0 0.95%2 1.0 3411 37 31 33 27 3s 29 37 100 1o None 34:1 37 2s 3619 32 23 33 99.9 1.2%M 3.9% Zn, balance Mg" 0.1 34:1 42 49 24 35 34 4199.5 do 0.5 3411 40 45 27 40 34 43 99.0 .do.. 1.0 34:1 45 42 49 32 45 4049 91.0 ...do 3.0 3411 39 45 50' 35 44 41 49 9 94.0 do 0.0 341 47 42 4441 52 43 52 B1nnk3 100 .do None 341 41 42 49 29 39 3s 44 10 99.0 1.03%Zn,0.62% Ca, balance Mg 1.0 64:1 40 34 41 22 3e 25 37 Blank 4.... o None04=1 40 31 40 20 33 21 3s 1 0.77% Zn, 0.147 Cu balanceM 1.0 150:1 37 3033 27 3s 23 3s 13 1mm; 5-.-. 10 do N e 1501 6 3; 2% i4 23 3s .3 150:1 24 Blank 6..-. None 1501 "{24 41 42 49 22 32 TYS=tensile yield strengthdefined as the load at which the stress TS tensile strength.

Fig. 3 is a similar view to Fig. 1 showing another modification of theapparatus.

As shown, the apparatus comprises, in its three forms, an extrusioncontainer I adapted to confine a charge 2 of the mixture of metalparticles to be compacted and extruded. The container is provided with aheating element 3, In Fig. 1, one end of the container l is closed'bythe die plate 4 in which is provided the die opening 5. In this form ofthe apparatus, the charge 2 is caused to be compacted in the containerand extruded through the die opening 5 by application of pressure bymeans of the dummy block 6 forced into the bore 1 of the container bythe ram 8 to form the extrusion 9.

In the form of the apparatus shown in Fig. 2, the container I is closedat one end by the plate I0. The other end of the container received thedie block I I carried by the hollow ram I2 which forces the die blockinto the container causing the charge 2 to be compacted and to extrudethrough die opening I3 to form the extrusion I4 which extends into boreI5 of the hollow ram In the modification of Fig. 3, the container isclosed at one end with a plate I6. The charge 2 is extruded as a tubularextrusion I7 through the annulus I8 around the die block I9 while it isforced into the container by the ram 20.

The forms of the apparatus shown are conventional.

F. followed by heat treating for 16 hours at 350 F.

curve deviates 0.2% from the modulus line.

In making the composite alloys shown in the foregoin table, thezinc-containing magnesiumbase alloys used were in atomized form theparticles of which were of various sizes substantially all passingthrough a 20 mesh sieve while being retained on a 200 mesh sieve. Theparticles of the particulated aluminum were of generally finer size thanthose of the magnesium alloy. The two particulated metals were mixedtogether in the proportions indicated and the mixture charged into theheated container of a ram ex truder of the type illustrated in Fig. 1.For the blanks, the zinc-containing magnesium alloy in the sameparticulated form as used in the mixtures was extruded alone undercomparable extrusion conditions. The rate of extrusion of the examplesnumbered 1 to 10, inclusive, and Blanks 1, 2, 3 and 4 was about 2 linealfeet of extrusion per minute. In Example 11 and Blank 5, the rate ofextrusion was 5 lineal feet per minute. In Example 12 and Blank 6, therate of extrusion was 15 lineal feet per minute.

Among the advantages of the invention are that a workable metal productis obtained having the light weight characteristic of magnesiumbasealloys but with enhanced strength, which is generally retained orincreased by a more or less prolonged (e. g. 1 to 20- hours) heating inthe temperature range of about 300 to 800 F. This property enables thecomposite alloy to be hot worked in the foregoing temperature rangewithout loss of strength.

We claim:

1. The method of making a solid composite high strength metal productwhich consists in forming a m'xture of two particulated metals, oneconsistin of aluminum in amount from 0.1 to 6 per cent of the weight ofthe mixture, the other forming the balance of the mixture and consistingof a magnesium-base alloy containing 05 to 8 per cent of zinc, up to 2.5per cent of manganese, up to 1 per cent of calcium, and up to 0.5 percent of copper, the balance of the alloy being magnesium, and dieexpressing the mixture at a temperature between 600 and 800 F'.

2. A composite metal body consisting of two particulated metals oneconsisting of aluminum in amount from 0.1 to 6 per cent of the weight ofthe body, the other forming the balance of the body and consisting of amagnesium-base alloy containing 0.5 to 8 per cent of zinc, up to 2.5 percent of manganese, up to 1 per cent of calcium, up to 0.5 per cent ofcopper, the balance of the alloy being magnesium, the particles beingelongated, orientated in the same direction, and welded together into anintegral solid.

THOMAS E. LEONTIS. ROBERT S. BUSK.

6 References Cited in the file of this patent UNITED STATES PATENTSOTHER REFERENCES Treatise on Powder Metallurgy by Goetzel, vol. 2, pp.500, 740, 741. Published in 1950.

Symposium on Powder Metallurgy, Buffalo Spring Meeting, March 3, 1943,published by American Society for Testing Materials, Philadel- 25 phia,Pa., pages 42 and 43.

2. A COMPOSITE METAL BODY CONSISTING OF TWO PARTICULATED METALS ONECONSISTING OF ALUMINUM IN AMOUNT FROM 0.1 TO 6 PER CENT OF THE WEIGHT OFTHE BODY, THE OTHER FORMING THE BALANCE OF THE BODY AND CONSISTING OF AMAGNESIUM-BASE ALLOY CONTAINING 0.5 TO 8 PER CENT OF ZINC, UP TO 2.5 PERCENT OF MANGANESE, UP TO 1 PER CENT OF CALCIUM, UP TO 0.5 PER CENT OFCOPPER, THE BALANCE OF THE ALLOY BEING MAGNESIUM, THE PARTICLES BEINGELONGATED, ORIENTED IN THE SAME DIRECTION, AND WELDED TOGETHER INTO ANINTEGRAL SOLID.